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Physiology > Physiology Block 3 Week 17 18 Sleep > Flashcards

Physiology Block 3 Week 17 18 Sleep Flashcards

1
Q

What is sleep?

A

unconsciousness from which the person can be aroused by sensory or other stimuli.

Required activity

An active process involving characteristic physiological changes in the organs of the body

Highly organized sequence of events that follow a regular, cyclic program each night.

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2
Q

Are sleep, anesthesia, or coma the same?

A

They do not exhibit the same brain wave patterns characteristic of true sleep

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3
Q

What does sleep deprivation cause in humans?

A

Impairs cognition
-dec cerebral glucose utilization and blood flow

Nonspecific neural and physiological symptoms

  • complaints
  • changes in EEG
  • increased sensitivity to painful stimuli
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4
Q

Proposed Functions of sleep

A
  1. Restoration and recovery of body systems as well as replenish energy stores while repairing itself after periods of energy consumption
  2. To conserve energy
    - -metabolic rate decreases during sleep
    - -“sleep = energy used per day’
  3. REM needed for memory consolidation, reinforcement of learning, and clearing unneeded memories
  4. Required for brain development and formation of brain synapses
    - -high REM in newborns
  5. Discharge of emotions
    - -dreaming in REM may provide safe discharge of emotions
    - -muscular paralysis prevents acting out dreams
    - -regions that control emotions, decision making, and social interaction reduced = relief from stress?
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5
Q

Do species with greater sleep times have higher or lower metabolic rates?

A

Higher

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6
Q

In humans, do sleep time and metabolic rate stay constant?

A

No, both decrease with age

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7
Q

How does sleep affect ability to retain/recall information?

A

humans who get plenty of NREM sleep in the first half of the night and REM sleep in the second half improve their ability to perform spatial tasks and to retain/recall information obtained the previous day

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8
Q

How is arousal assessed?

A

Electrical activity reflecting activity of neuronal populations and not the activity of individual neurons

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9
Q

How is the electrical activity of awake state characterized?

A

alpha rhythm of 8 to 13 Hz

5-100 mv wave amplitude

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10
Q

How is the electrical activity of sleep state characterized?

A

High amplitude and low frequency (0.5 to 4Hz) during stage 3 and 4 sleep

Thought to reflect a slowing and synchronous discharge of neurons.

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11
Q

What is delta sleep?

A

Deep sleep

Arousal is more difficult than stage 1 and 2, which have theta rhythm 4-7 Hz

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12
Q

During NREM sleep, are the muscles functional?During REM sleep?

A

NREM: Muscles are function, but activity is low

REM: skeletal muscle activity is absent, but heart, diaphragm, eye muscles, and smooth muscles remain functional

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13
Q

How is REM sleep characterized?

A

High frequency and low amplitude

Reflect high and desynchronized cortical activity

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14
Q

NREM: Somatic Activity

A

Few motor events

Body repositioning

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15
Q

REM: Somatic Activity

A

Paralysis (Tonic)

  • post synaptic inhibition of motorneurons
  • hyperpolarization of motorneuron membranes

Phasic

  • rapid eye movements
  • muscle twitches
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16
Q

NREM: CNS Activation

A

Mean discharge rate of neurons decreased

Cerebral glucose utilization decreased overall

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17
Q

REM: CNS Activation

A

Mean discharge rate of neurons INCREASED in many regions

  • PGO spikes
  • Rapid Eye movements

Cerebral glucose utilization increased

Cerebral blood flow greatly increased

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18
Q

Hypnogram: Young Adults

A

Five 90 minute cycles alternating between NREM and REM sleep with brief arousals

Deepest stage of NREM occur in first part of night

Episodes of REM becomes longer as night progresses

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19
Q

Tonic REM sleep

A

Periods of sustained postural muscle atonia + bursts of eye movements

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20
Q

Phasic REM sleep

A

Postural muscle twitches

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21
Q

When do dreams occur?

A

REM sleep aka paradoxical sleep

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22
Q

Ultradian Rhythm

A

rhythm occurring within a period of less than 24 hours

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23
Q

Are sleep patterns of children and elderly the same as young adults?

A

No, they differ

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24
Q

What happens to total sleep time and percent REM sleep with increased age?

A

They decrease

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25
Q

REM: infants

A

High percent of REM sleep

The predominance of REM in infants is thought to reflect synaptic and brain development that occur at these ages.

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26
Q

REM: elderly

A

Fragmented and relatively reduced sleep time in elderly

The pattern in the elderly probably reflects a gradual deterioration with aging (as occurs in all organs) of sleep control mechanisms resulting in multiple sleep problems

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27
Q

What happens if sleep debt not paid? Can caffeine help?

A

Not meeting sleep needs still allows us to function, but motor and cognitive functions are impaired.

Caffeine cannot substitute for sleep because only counteract some of the effects of sleep deprivation.
-attenuates adenosine receptor activity promoting wakefullness

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28
Q

How is sleep regulated?

A

2 process model:

Homeostatic process
-the longer the organism is awake, the greater propensity to sleep

Circadian component
-oscillatory process that affects propensity for sleep and waking

29
Q

Internal Biological Clock

A

26-hour period–makes us sleepy at night and awake during the day

10,000 neurouns in suprachiasmatic nucleus (SCN) of hypothalamus

  • Regulates endogenous biological rhythms and is reset to match the day length by the environmental photoperiod
  • mediated by photoreceptors in retina, sending signals to SCN
  • pineal gland (SCN controlled) increases melatonin at night = promote sleep
30
Q

What happens to sleep/wake cycle when removed from environmental cues?

A

the cycle is lengthened and the individual goes to bed later each night

several days later he is going to bed the same time as the first night

Cues normally maintain 24 hour sleep-wake cycle

In absence of cues, circadian clock has 26.1 hour sleep-wake cycle

31
Q

As time in awake state increases, what happens to drive to sleep?

A

Increases

32
Q

Adenosine

A

Sleep promoting factor

Levels increase with wakefulness as a result of ATP and ADP breakdown

Attenuating adenosine receptor activity with caffeine promotes wakefulness

33
Q

Cytokines

A

Sleep promoting

May explain why diseased conditions result in increased durations of sleep

34
Q

Serotonin

A

Wake and Sleep promoting

there is evidence that drugs which block the formation of serotonin results in sustained wakefulness

35
Q

What wakefulness promoting substances decrease during NREM?

A

serotonin, norepinephrine, histamine

These normally inhibit cholinergic neurons in the rostral pontine laterodorsal tegmental and pedunculopontine tegmental nuclei (PPT/LDT).

Released from inhibition, initiate and sustain REM sleep.

36
Q

Lesions in ____ cause?

  • -lateral hypothalamus
  • -2 more caudal sites
  • -pontomesencephalic junction
  • -spinomedullary junction
A

Multiple brain sites contribute to the normal sleep-wake cycle

Lateral hypothalamus: narcolepsy

2 more caudal sites: insomnia

Critical role of the pons and medulla in regulating the sleep-wake cycle

Pontomesencephalic junction: comatose

spinomedullary junction: no effect

37
Q

Ascending Arousal Systems

A

Ascending projections from brainstem and posterior hypothalamus to forebrain, cortical, subcortical targets

Excitatory inputs from many regions and neurotransmitters

OREXIN neurons innervate ascending arousal system and cerebral cortex

38
Q

NREM and REM Sleep Pathways

A

Multiple neurochemicals contribute to initiating and maintaining NREM and REM sleep stages of sleep:

  • aminergic inputs inhibit cells in PPT/LDT during W and NREM sleep
  • NREM sleep inhibition of arousal systems by GABA and galanin from VLPO
  • REM sleep driven by predominantly cholinergic neurons
  • Aminergic inputs fall silent during REM sleep, disinhibiting PPT/LDT
  • REM sleep produces atonia and descending inhibitory inputs to motor neurons and activates the thalamus
39
Q

How do the brainstem and hypothalamic circadian rhythm promote wakefulness?

A

Brainstem:
Increased NE
Increased 5-HT
Decreased ACh

Hypothalamus:
Increased activation of the thalamus and cortex
Increased histamine
Decreased GAMA

40
Q

How do the brainstem and hypothalmic circadian rhythm result in NREM sleep?

A

Decreased activation of the thalamus and cortex
Increased GABA
Decreased histamine

41
Q

How do the brainstem and hypothalmic circadian rhythm result in REM sleep?

A

REM sleep occurs when reduced norepinephrine and serotonin release inhibition of pontine PPT and LDT cholinergic neurons which activate the REM system

Decreased NE
Decreased 5-HT
Increased ACh

42
Q

NREM: Blood Flow

A

Little change in cutaneous, muscular, and mesenteric vascular blood flow

State of resting brain activity, reduced neuronal activity, decreased synaptic transmission, and decreased cerebral metabolism

Cerebral blood flow decreases 5-25%

43
Q

REM: Blood Flow

A

Vasodilation in mesenteric and renal vascular beds = increased flow

Vasoconstriction in skeletal muscular and cutaneous vascular bed = decreased flow

State of active brain, increased neuronal activity, and increased cerebral metabolism

Cerebral blood flow increases up to 40%

44
Q

NREM: Blood Pressure

A

BP falls 5-15%

45
Q

REM: Blood Pressure

A

BP fluctuates–unstable during phasic REM due to phasic vagal inhibition and sympathetic activation

46
Q

NREM: Peripheral vascular resistance

A

Unchanged or slightly falls

47
Q

REM: Peripheral vascular resistance

A

Decreases due to vasodilation

48
Q

Hemodynamic changes

A

Parasympathetic innervation in NREM and REM

HR and CO dec

Cerebral blood flow

  • NREM: dec
  • REM: inc

Phasic REM
–BP and HR unstable due to phasic vagal inhibition and sympathetic activation

Overall slight decrease in total vascular resistance during sleep

49
Q

NREM: Ventilation

A

Small decreases by 0.5-1.5 due to secondary reduction in total volume

Respiratory pattern is stable and rhythmic

50
Q

REM: Ventilation

A

Decreases, but not as much as NREM
–mostly seen in phasic REM

Respiratory pattern is irregular
–during phasic

51
Q

Ventilation/Rrespiration changes

A

Decrease in ventilation and respiration

Decrease in VCO2 and VO2 during sleep

Metabolism slows at sleep onset and accelerates at 5AM

During sleep, ventilation decreases proportional to metabolism

Increase in PaCO2 due to alveolar hypoventilation

Blunted hypoxic and hypercapnic responses

52
Q

NREM: Thermal Regulation

A

Body temp begins to fall at sleep onset
Tend to awake on rising phase of core body temp

Lowest during 3rd NREM/REM cycle

NREM: Sweating and shivering

53
Q

REM: Thermal Regulation

A

Body temp begins to fall at sleep onset
Tend to awake on rising phase of core body temp

Lowest during 3rd NREM/REM cycle

REM: no thermoregulation

54
Q

REM/NREM: Limb Muscles

A

Muscle Tone

  • Awake: Maximal
  • NREM: decreased
  • REM: very decreased/absent. Atonia of skeletal muscles (except diaphragm)
55
Q

REM/NREM: Upper Airway muscles

A

Reduction of dilator muscle (palatal, genioglossal) tone or activity during NREM with further reduction in REM

Increase in upper airway resistance and narrowing of upper airway space

56
Q

Gastric acid secretion

A

Circadian rhythm
peaks between 10PM-2AM
No relationship with different sleep stages

57
Q

Gastric motility

A

Overall inhibition of gastric motor function during sleep

58
Q

Growth Hormone

A

Concentrations peak 90 mins after sleep onset

Higher in men

Duration of 1-3 hours

Sleep deprivation suppresses GH secretion

59
Q

Parathyroid Hormone

A

Increased levels during sleep compared to awake state

Peaks between 2AM-4AM

60
Q

ACTH

A

Cortisol decreases with sleep onset

Cortisol levels lowest in early part of sleep, higher from 4AM-8AM

61
Q

Prolactin

A

Sleep dependent pattern

Highest conc during sleep

Levels begin to rise 60-90 mins after sleep onset

Higher in women

Peaks from 5AM-7AM

62
Q

Gonadotropic Hormone

A

During pre-puberty and puberty stages in boys and girls, increase during sleep

Testosterone rise at sleep onset and continue throughout sleep

No clear relationship in FSH and LH

63
Q

Thyroid Stimulating Hormone

A

Low in awake state
Inc in the evening
Peak before sleep onset

TSH secretion inhibited by sleep and delcines

64
Q

Aldosterone

A

Increased during sleep

Peaks prior to sleep OFFSET

65
Q

Melatonin

A

Begins to rise in evening and peaks between 3AM-5AM

Highest levels correspond to lowest core body temp

66
Q

Antidiuretic Hormone

A

Episodic secretion

NO RELATIONSHIP to sleep

67
Q

Which statement below is incorrect regarding REM sleep?

The breathing pattern is less regular than during NREM sleep.

The discharge rate of serotoninergic neurons in the raphe pallidus decreases below wakefulness during REM sleep.

Sweating and shivering do not occur during REM sleep.

Skeletal muscle tone is decreased from wakefulness during REM sleep.

Upper airway muscle activity is less during REM sleep than in the awake state.

A

All true

68
Q

Which of the following pattern of changes in central neuotransmitters or neuromodulators is associated with the transition from NREM sleep to wakefulness?

Decrease in norepinephrine, increase in serotonin, increase in acetylcholine, decrease in histamine and decrease in GABA.

Decrease in norepinephrine, increase in serotonin. Increase in acetylcholine, decrease in histamine and increase in GABA.

Decrease in norepinephrine, decrease in serotonin, increase in acetylcholine, increase in histamine and increase in GABA.

Increase in norepinephrine, increase in serotonin, decrease in acetylcholine, increase in histamine, and decrease in GABA.

Increase in norepinephrine, decrease in serotonin, decrease in acetylcholine, increase in histamine, and decrease in GABA.

A

Increase in norepinephrine, increase in serotonin, decrease in acetylcholine, increase in histamine, and decrease in GABA.

69
Q

Regarding hemodynamic changes that occur from wakefulness to different stages of sleep, all of the below occur except:

During phasic REM sleep, blood pressure and heart rate are unstable due to phasic vagal inhibition and sympathetic activation.

Cerebral blood flow decreases in NREM and increases in REM sleep.

There is a decrease in total peripheral resistance from wakefulness to NREM sleep.

The sympathetic system dominates over the parasympathetic system during NREM and REM sleep.

During REM sleep, there is vasoconstriction of muscular vascular beds decreasing blood flow below NREM sleep.

A

The sympathetic system dominates over the parasympathetic system during NREM and REM sleep.

Physiology (20 decks)

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